Vibronic quantum beats in PbS microcrystallites

Abstract

We have used femtosecond optical spectroscopy to study the dynamics of excitons strongly confined in microcrystallites of the narrow-band-gap semiconductor PbS. The transient absorption of the lowest exciton level exhibits terahertz-frequency vibronic quantum beats. Far-infrared measurements show that the vibrations are confined transverse-optical phonons.